The present invention relates to a centering device for two elements rotating one with respect to the other, comprising at least first and second radial bearings situated at a distance one from the other along the axis of the rotor and each one being constituted of first and second opposing centering members with angular contact between inner and outer races.
A large number of mechanisms equipped with bearing assemblies such as ball bearings or needle bearings are designed to operate in a calm environment without vibrations. But, generally, such mechanisms are often subjected during phases where they are not working, and in particular during a transport, to vibrations and to strong shocks. It is well known that bearings are very responsive to shocks and to vibrations, especially when there is no rotation of the rotor supported by the bearings. It is precisely the object of the present invention to propose devices which permit to isolate the bearings from external vibrations during their rest period, or which permit to guarantee a reliable operation both in a first phase of transitory operation of limited duration corresponding to severe conditions of environment and in a second phase of operation demanding great accuracy.
Such systems whereby a rotor can be locked in a rest position or if necessary kept rotating whilst relieving the main bearings from the effort of supporting the rotor, are particularly useful in the space domain where mechanisms are subjected to a vibratory phase during launching and are thereafter required to operate in space, without any breakdowns, i.e. without vibrations especially. Of course many other applications are known on land, for example, the assembling of precision mechanisms such as transportable optical devices or aerial directing systems.
An example of a known device for locking a rotor and partly unloading bearing assemblies comprises a rotor mounted in a frame by means of a first bearing means constituted by a first bearing assembly with angular contact and a second bearing means constituted by a second bearing assembly of the angular contact type, i.e. with bearing ball contacts forming with a radial plane of the rotor, a certain predetermined angle of contact.
In his case, complementary conical portions are formed on parts which respectively support the rings of the first bearing assembly. When the rotor is not in operation, an axial force is applied on said rotor in order to bring the conical portion of the rotor on the conical portion of the stator, so that the rolling elements of the first bearing assembly are entirely unloaded. Such a system however does not ensure any reduction of the loading force exerted on the rolling elements of the second bearing assembly by the rotor and therefore it does not allow for complete unloading of the bearing assemblies.
Assemblies are also known which comprise radial bearings each one comprising at least first and second, opposing angular contact bearing assemblies, i.e. bearing assemblies adapted to exert axially opposed forces. Such types of bearing assemblies are not however unloadable and therefore cannot permit the locking of a rotor in a rest position in such a way as to ensure that the bearing assemblies are well preserved.
It is the object of the invention to overcome the drawbacks of the prior devices and to procure an assembly whereby when a rotor is not in operation, it is safely locked in position and all the different rolling elements of the main bearing assemblies used are completely unloaded, thus reducing the risks of damages to them through shocks or vibrations to which the whole device assembly could be subjected.
A further object of the invention is to allow the use of a rotor for transmitting signals, when the rotor is in the locked position according to the assembly of the present invention.